Preparation and characterization of corn starch-based film: effect of citric acid or sunflower oil and its combination

The properties of starch-based edible film prepared in the absence and the presence of citric acid; as cross-linking agent (chemical modification) and/or sunflower oil; as barrier enhancer (physical modifier) were investigated. Films containing citric acid had higher tensile strength (TS) but lower elongation at break (EB), while the films incorporated with sunflower oil showed lower TS but higher EB than the control film (p < 0.05). Moreover, the film in the presence of the combination of sunflower oils and citric acid showed a lower EB, as compared to control. Water vapor permeability was decreased to 2.86–2.93 g mm/m2 day Pa × 10–7 when sunflower oil was added, while control film and the films containing citric acid showed the higher water vapor permeability which are 4.42 and 3.15–3.99 g mm/m2 day Pa × 10–7, respectively. FTIR spectra indicated that films added citric acid induced the film cross-linking, as evidenced by a higher amplitude at the wavenumber of 1746 cm−1. Films added with sunflower oil had opaque, and rough cross-section as compared to other films. Thus, these findings showed that using citric acid or sunflower oil alone to modify the properties of starch-based films had better performance than its combination.